Final answer:
The Healthcare Cost and Utilization Project (HCUP) is the national database that includes data on all discharged patients, comprising the largest collection of longitudinal hospital care data in the United States for various health care applications.
Step-by-step explanation:
The national database that includes data on all discharged patients regardless of payer is known as the Healthcare Cost and Utilization Project (HCUP). HCUP is a family of health care databases and related software tools and products developed through a Federal-State-Industry partnership and sponsored by the Agency for Healthcare Research and Quality (AHRQ). HCUP databases bring together the data collection efforts of State data organizations, hospital associations, private data organizations, and the federal government to create a national information resource of patient-level health care data.
HCUP includes the largest collection of longitudinal hospital care data in the United States, with all-payer, encounter-level information beginning in 1988. This expansive dataset includes data on inpatient hospital stays, emergency department visits, and ambulatory surgeries. Health professionals and researchers use HCUP for various applications, including research on health care utilization, access, charges, quality, and outcomes.